No abstract

The crystal structure, magnetic and electrical transport properties of the sodium-doped lanthanum manganites La1-xNaxMnO3 (0.07⩽x⩽0.40) have been studied in detail using x-ray powder diffraction, atomic absorption spectroscopy, a SQUID (superconducting quantum interference device) magnetometer and the four-probe resistivity measurement technique. A rhombohedrally distorted perovskite structure has been observed in the range 0.07⩽x⩽0.20. Both the lattice parameter and unit-cell volume decrease with increase in the Na content. A ferromagnetic-to-paramagnetic phase transition associated with a metal-insulator transition is observed for all the La1-xNaxMnO3 compounds. There is a systematic change in both the Mn-O-Mn bond angle and the tolerance factor with Na content. The compositional variation of the magnetic and metal-insulator transition temperatures is explained as due to the distortion of the MnO6 octahedron and increase in the tolerance factor that controls the hopping interaction. In the metallic region a ρ~AT2 behaviour is observed due to the magnon excitation effect. The resistivity shows a field-dependent minimum at low temperature that has been explained as due to the intergrain transport phenomenon.

Autophagy is significantly enhanced in locomotor muscles of stable patients with COPD. The degree of autophagy correlates with severity of muscle atrophy and lung function impairment.

Polybrominated diphenyl ethers (PBDEs) have the potential to disrupt the thyroid endocrine system. The objective of the present study was to characterize the disrupting effects of longterm exposure on the thyroid endocrine system in adult fish and their progeny following parental exposure to PBDEs. Zebrafish (Danio rerio) embryos were exposed to environmentally relevant concentrations (1, 3, and 10 μg/L) of the PBDE mixture DE-71 for 5 months until sexual maturation. In the F0 generation, exposure to DE-71 significantly increased plasma thyroxine (T4) but not 3,5,3 0 -triiodothyronine (T3) in females. This increased T4 was accompanied by decreased mRNA levels of corticotropinreleasing hormone (CRH) and thyrotropin β-subunit (TSHβ) in the brain. The F1 generation was further examined with or without continued DE-71 treatment conditions. Exposure to DE-71 in the F0 fish caused significant increases in T4 and T3 levels in the F1 larvae and modified gene expressions in the hypothalamicÀ pituitaryÀthyroid axis (HPT axis) under both conditions. Decreased hatching and inhibition of growth in the F1 offspring were observed in the condition without DE-71 treatment. Continued DE-71 treatment in the F1 embryos/larvae resulted in further decreased hatching, and increased malformation rates compared with those without DE-71 exposure. Analysis of F1 eggs indicated that parental exposure to DE-71 could result in a transfer of PBDEs and thyroid hormones (THs) to their offspring. For the first time, we demonstrated that parental exposure to low concentrations of PBDEs could affect THs in the offspring and the transgenerational PBDE-induced toxicity in subsequent nonexposed generations.

31Organophosphate flame retardants are emerging environmental contaminants, 32 although knowledge of their health risks is limited. Here, thyroid hormone 33 homeostasis and neuronal development was studied in the progeny of adult zebrafish 34 exposed to tris (1, 3-dichloro-2-propyl) phosphate (TDCPP). Adult zebrafish were 35 exposed to TDCPP (0, 4, 20, and 100 µg/L) for 3 months. Increased generation of 36 reactive oxygen species and reduced survival rates was observed in exposed F1 larvae. 37We also observed a significant decrease in plasma thyroxine and amino butyric acid and histamine. Larval locomotion was significantly decreased in 43 exposed fish, but there was no effect on acetylcholinesterase activity. 44Bioconcentration of TDCPP was observed in F0 fish. TDCPP was also detected in F1

No abstract

We aimed to evaluate the exposure of neonates to polybrominated diphenyl ethers (PBDEs) from a primitive e-waste (obsolete electrical and electronic devices) recycling area, in Guiyu, China, and a control area, Chaonan, China, through umbilical cord blood (UCB), the health effects, and relevant factors. Questionnaires were addressed, and UCB was collected shortly after birth from 153 pregnant women between May and July 2007. Blood samples were prepared by liquid-liquid extracting methods. PBDE concentration was determined by gas chromatography/mass spectrometry in the electron capture negative ionization mode. The total PBDE concentration was higher in UCB samples from Guiyu than in Chaonan samples (median 13.84, range 1.14-504.97 ng g(-1) lipid, vs 5.23, range 0.29-363.70 ng g(-1) lipid) (p < 0.05). BDE-209 was the dominant PBDE congener, followed by BDE-47, -153, and -99. Residence in Guiyu, which is a site for e-waste recycling, involvement in e-waste recycling, and the residence also being used as a family workshop were significant factors contributing to PBDE exposure. PBDE levels significantly differed in neonates by normal birth and adverse birth outcomes including stillbirth, low birth weight, and premature delivery (p < 0.05). The neonates from Guiyu are exposed to high levels of PBDEs. Prenatal exposure to PBDEs may affect neonates' health in Guiyu, which still needs to be evaluated in larger epidemiological studies.

No abstract